Control valve and system

ABSTRACT

A brake system for a vehicle having a brake adapted for energization in response to a spring setting pressure released actuator connected therewith is provided with a push-pull type control valve which is selectively operable to control the application and exhaustion of emergency pressure to and from said brake actuator to effect the de-energization and energization of said brake, and said control valve is automatically actuated in response to a predetermined low service pressure subjected thereto to exhaust the emergency pressure from said brake actuator to effect the spring set energization of said brake. The control valve is provided with resiliently urged means automatically actuated in response to a predetermined low service pressure acting thereon to isolate the emergency fluid pressure applied through said control valve from that supplied thereto and vent the applied emergency fluid pressure to the atmosphere, and said resiliently urged means is also selectively operable to override the automatic actuation thereof.

United States Patent 11 1 Stearns 1451 July 17, 1973 CONTROL VALVE ANDSYSTEM [75] Inventor: George W. Stearns, St. Louis, Mo. [57] ABSTRACTAssignee! Wagner Electric Corporation, A brake system for a vehiclehaving a brake adapted for Newark, NJ. energization in response to aspring setting pressure re [22] Filed: AP 27, 1971 leased actuatorconnected therewith is provided with a push-pull type control valvewhich is selectively operal PP ,798 ble to control the application andexhaustion of emergency pressure to and from said lbrake actuator to ef-52 11.5. CI 303/71 137/6242? 303/9. fect the de'energizafion andenergized (Said brake 3O3/|3 and said control valve is automaticallyactuated in re- 511 Int. Cl B60t /16 Sponge predetermined Service PmSure58 Field of Search 251/94; l37/624.27; Jected 161cm m exhaust theemergency Press"re fmm 303/68, 7| 36 9 13 said brake actuator to effectthe spring set energization i of said brake. The control valve isprovided with resil- [56] References Cited iently urged meansautomatically actuated in response to a predetermined low servicepressure acting thereon UNITED STATES PATENTS to isolate the emergencyfluid pressure applied through said control valve from that suppliedthereto and vent 3504'946 4x970 Q the applied emergency fluid pressureto the atmo- 3'5O4947 4/1970 Va'emine 56 X sphere, and said resilientlyurged means is also selec- 351 1 276 5/1970 .lessen et51111IIIIII.......1IIi"i31/624.21 tively Operable to override theaummatic actuation thereof. 5337 2; f ji g g gzii s Reger 24 Claims, 6Drawing Figures 32 29 9 50 64 R 22 37 i l. 148 l4/l i 1. 5., 52. J1-744i 4 44 33 l i 3 38 l 25 ,27

CONTROL VALVE AND SYSTEM This invention relates generally to controlvalves and in particular to push-pull type control valves for use in afluid pressure system to control a spring set brake actuator thereof.

BACKGROUND OF THE INVENTION In the past, tripping or automaticallyactuated pushpull type control valves have been utilized in fluidpressure systems for controlling the application and exhaustion ofemergency fluid pressure to and from a fluid pressure responsive springset brake actuator to effect the desired de-energization andenergization thereof; however, the main undesirable or disadvantageousfeature of such past control valves and systems was that said controlvalve sensed or was automatically responsive to the same emergency fluidpressure which it delivered to the system.

SUMMARY OF THE INVENTION The principle object of the present inventionis to respectively provide a brake system and a control valve thereforwhich overcomes the aforementioned undesirable and disadvantageousfeature of such past brake systems and control valves, and this, as wellas other objects and advantageous features of the present invention,will become apparent hereinafter.

Briefly, the invention includes a brake system having a brake adaptedfor spring set energization by a spring setting pressure releasedactuator in response to emergency pressure applied thereto less than apredetermined value, and means automatically actuated in response toservice pressure subjected thereto less than a predetermined value forventing the emergency pressure applied to said actuator including othermeans for overriding the automatic actuation of said first named means.The invention also comprises a control valve having application meansautomatically actuated in response to a predetermined minimum value ofcontrol fluid pressure acting thereon to isolate the fluid pressureapplied through said control valve from that sup plied thereto and ventthe applied fluid pressure to the atmosphere, and said application meansincluding means selectively operable to override the automatic actuationof said application means.

DESCRIPTION OF THE DRAWINGS In the drawings which illustrate embodimentsof the invention and wherein like numerals refer to like parts whereverthey occur:

FIG. 1 is a schematic view of a fluid pressure system embodied in thepresent invention;

FIG. 2 is a sectional view illustrating the control valve of FIG. I,also embodied in the present invention, in its automatically actuated orout" position in crosssection;

FIG. 3 is a sectional view illustrating the control valve of FIG. 2 inits "in" position in cross-section;

FIG. 4 is a schematic view illustrating another fluid pressure systemalso embodied in the present inven tion;

FIG. 5 is a partial schematic view of an alternative fluid pressuresystem also embodied in the present invention; and

FIG. 6 is a sectional view illustrating the switching valve of FIG. 5embodied in the present invention in cross-section.

Referring now to the drawings in detail and in particular to FIG. 1, adual fluid pressure or brake system 1 is shown for use on a vehiclehaving at least one spring setting pressure released brake cylinder oractuator 2 of a type well known in the art and including an emergency orspring set portion 3 and a service or fluid pressure responsive or motorportion 4 for energizing a vehicle brake (not shown). The system 1 isprovided with service and emergency branches, indicated generally at 5,6, and said service branch includes a service reservoir 7 connected withthe fluid pressure responsive motor 4 of the brake actuator 2 byconduits 8, 8a, having the inlet and outlet sides of an operatoractuated foot application valve 9 of a type well known in the artserially interposed therebetwee-n. The emergency branch 6 includes anemergency reservoir 10 which is connected to the spring set portion 3 ofthe brake actuator 2 by conduits 11, 11a having the inlet and outletports of a push-pull type control valve 12 serially interposedtherebetween, and a control conduit 13 has one end connected to thecontrol port of said push-pull control valve while the other end thereofis connected to the conduit 8 between the service reservoir 7 and application valve 9. To complete the description of the system 1, anotherconduit 14 having a uni-directional or one-way check valve 15 interposedtherein is connected between the service and emergency reservoirs 7, l0,and fluid pressure generating means, such as a compressor 16, isconnected to said service reservoir by a conduit 17.

Referring now to FIG. 2, the control valve 12 is provided with a housing20 having a bore 21 defining a valve seat therein. A counterbore 22 isalso provided in the housing 20 coaxial with the bore 21 and definingtherewith an annular shoulder or abutment 23 on said housing, andopposed stepped counterbores 24, 25, 26 are also provided in saidhousing c-oaxially aligned with said bore, said bore and counterbore 20,24 and said counterbores 24, 25 having shoulders or abutments 27, 28respectively defined therebetween on said housing. A closure member orend plug 29 having axial bore 30 therethrough is threadedly received inthe leftward end of the counterbore 26, and another closure member orend plug 31 having a bore 32 defining a valve seat therein and exhaustport 33 connected with said bore is threadedly received in the rightwardend of the counterbore 22. Inlet and outlet ports or supplied andapplied fluid pressure ports 34, 35 which are interposed in the conduit11, as previously mentioned, are provided in the housing 20 intersectingwith the counterbores 24, 22 adjacent to shoulders 23, 27, respectively,and a control port 36 which receives the conduit 13, as previouslymentioned, is also provided in said housing intersecting with thecounterbore 26.

A selectively operable or application member, such as the push-pull rodindicated generally at 37, is provided with an exteriorally extending,operator applied force receiving portion, such as the knob 38, and saidrod is slidably received in the housing and closure member bores 24, 30carrying peripheral seals 39, 40 in sealing engagement therewith,respectively. The push rod 37 is provided with an integral reducedextension 41 which extends through the housing bore and counterbores 21,22, 24 having a reduced free end portion 42 thereon in the closuremember bore 32. A piston 43 is retained on the extension free end 42against displacement by suitable means, such as the nut 44, and

said piston is normally displaced from sliding engagement with theclosure member bore 32 toward abutment with the housing shoulder 23. Asea] or valve member 45 is peripherally carried on the piston 43 forsealing engagement with the closure member bore or valve seat 32 betweenthe outlet and exhaust ports 35, 33, and another seal or valve member 46is peripherally carried on the rod extension 41 normally being sealablyengaged with the housing bore or valve seat 21 to interrupt pressurefluid communication between the inlet and outlet ports 34, 35.

An automatic actuating or resiliently urged member, such as the controlpiston 47, is slidably received in the housing counterbore 25 carrying aperipheral seal 48 in sealing engagement therewith, and opposed ends orabutment surfaces 49, 50 are provided on said piston for abuttingengagement with a snap ring or driven shoulder or abutment 51 providedon the push rod 37 and the housing shoulder 28, respectively. An axialbore 52 is provided in the piston 48 intersecting with the opposed ends49, 50 thereof and in which the rod 37 is slidably received, and anotherseal 53 is peripherally carried on said rod in sealing engagement withthe piston bore 52. A spring 54 is pre-compressed between the housingshoulder 28 and the piston 47 urging the piston end 49 into drivingengagement with the rod abutment 51 to normally urge the rod 37 towardits out position, as shown and described in FIG. 2.

An expansible control chamber 55 is defined in the housing counterbores25, 26 between the closure member 29 and piston 47 in open pressurefluid communication with the control port 36, and an annular effectivearea A is defined on said piston in said control chamber by the sealingengagement of the seals 48, 53 with the housing counterbore 25 and thepiston bore 52, respectively. When the rod 37 is in its out" position,asshown in FIG. 2, an annular effective area A, defined between thesealing engagements of the seals 39, 46 with the housing counterbore andbore 24, 21, respectively, is provided on the rod 37 and subjected tothe fluid pressureat the inlet port 34 to establish a holding force Foacting to maintain said rod in its out" position. To complete thedescription of the control valve 12, when the rod 37 is in its in"position as shown in FIG. 3 and discussed hereinafter, another annulareffective area A opposed to area A, and defined by the sealingengagement of the seals 39, 45 with the housing counterbore 24 and theclosure member bore 32, is provided on said rod and subjected to thefluid pressure at the outlet port 35 to establish another holding forceFi acting to maintain said rod in its in" position.

OPERATION With the component parts of the control valve 12 in their out"positions as shown in FIG. 2 and described hereinbefore, fluid pressuregenerated by the compressor I6 flows through the conduit 17 into theservice reservoir 7 and therefrom through the conduit 14 and check valve15 into the emergency reservoir 10. The fluid pressure also flows fromthe service reservoir 7 through the conduits 8, 13 to the control port36 of the control valve 12 and therefrom into the control chamber 55acting on the area A, of the control piston 47. When the force Fs of theservice fluid pressure in excess of a predetermined value acting on thearea A, overcomes the opposing compressive force Fe of the spring 54,the control piston 47 is moved rightwardly against said spring toward aninoperative position disengaging the piston end 49 from the rod abutment51 and engaging the piston end 50 with the housing shoulder 28, as shownin FIG. 3.

In order to de-actuate the spring set portion 3 of the brake actuator 2and de-energize the brake (not shown), the operator applies a manualforce on the exterior end or knob 38 of the control valve push rod 37overcoming the holding force F0 to move said rod rightwardly toward itsin" position, as shown in FIG. 3. Movement of the rod 37 toward its inposition initially engages the valve member 45 with the valve seat 32interrupting pressure fluid communication between the outlet and exhaustports 35, 33 and thereafter disengages the valve member 46 from itsvalve seat 21 to establish pressure fluid communication between theinlet and outlet ports 34, 35. Of course, with the rod 37 in its in"position, the rod abutment 51 is repositioned adjacent to the controlpiston 47 in its inoperative position, and the holding force Fi replacesthe holding force Fo which is eliminated. With the inlet and outletports 34, 35 in open pressure fluid communication, emergency fluidpressure which is supplied from the conduit 11 to said inlet port flowstherefrom through the housing bore and counterbore 21, 22 to establishan applied or emergency fluid pressure at the outlet port 35 which flowstherefrom through the conduit 11a to the spring set portion 3 of thebrake actuator 2 to effect the deactuation thereof and thede-energization of the brake. When the rod 37 is in its in" position,the operator applied force is removed therefrom wherein the establishedholding force Fi will maintain said rod in the in position, and theservice force Fs acting on the control piston 47 will, of course,continue to contain the compressive force Fc of the spring 54.

In the event of failure of the service fluid pressure due to compressormalfunction, slow leaks, a ruptured conduit or the like in the servicebranch 5 of the system 1 wherein the service fluid pressure iseliminated or reduced to a value less than the predetermined value, theservice force Fs is, of course, eliminated or correspondingly reduced invalue, and the force Fc of the spring 54 is effective to automaticallyand concertedly drive the control piston 47 androd 37 leftwardly throughthe driving connection of the piston end 49 with the rod abutment 51from the in" position to the out" position of said rod. In this manner,the control valve 12 is automatically actuated wherein the valve member46 is moved leftwardly with the rod 37 to re-engage the valve seat 21and again isolate the supplied fluid pressure at the inlet port 34 fromthe applied fluid pressure at the outlet port 35, and the valve member45 is thereafter disengaged from its valve seat 32 to re-establishpressure fluid communication between the outlet and exhaust ports 35, 33to exhaust the emergency fluid pressure applied to the spring setportion 3 of the brake actuator 2 through the conduit 11a, said outletport, the closure member here 32 and said exhaust port to theatmosphere. When the applied emergency fluid pressure is so reduced, thespring set portion 3 of the actuator 2 is actuated to effect anemergency or spring setting'energization of the brake under theaforementioned emergency conditions, i.e. the loss or predeterminedreduction of the service fluid pressure.

Of course, if desired, the operator can override the automatic actuationof the control valve 12 by the control piston 47 upon the loss of theservice fluid pressure. The override is accomplished by re-applying andmaintaining a manual force on the exterior end 38 of the rod 37 tomanually move said rod to its in position, as previously described,against the compressive force Fc of the spring 54 acting on said rodthrough the driving connection of the engagement of the end 49 of thecontrol piston 47 with the rod abutment 51. It is, of course, desirableto override the automatic function of the control valve 12 in order totemporarily de-actuate the spring set portion 3 of the actuator 2 anddeenergize the brake to permit the movement of the vehicle to a safe orofi'-the-road position until the service branch 5 can be repaired andthe system 1 is once again operable. When the vehicle has been moved tothe desired safe location for the repair of the system 1, the manuallyapplied force is removed from the rod 37 wherein the compressive forceFc of the spring 54 is again operable to concertedly drive the piston 52and said rod to the out position thereof which again interrupts pressurefluid communication between the inlet and outlet ports 34, 35 andreestablishes venting communication between the outlet and exhaust ports35, 33 to again actuate the spring set portion 4 of the brake actuator 2and energize the brake, as described hereinbefore.

Referring now to FIG. 4, another fluid pressure system 100 is shown foruse in a tractor-trailer vehicle combination having substantially thesame component parts and functioning in substantially the same manner asthe previously described system 1 with the following exceptions.

In the system 100, a completely protected or auxilliary emergencyreservoir 101 is connected with the emergency reservoir by a conduit 102having a unidirectional flow or check valve 103 interposed therein, andanother conduit 104 is connected between said auxiliary emergencyreservoir 101 and the inlet side of a ratio-relay valve 105 of a typewell known in the art such as shown in the R. C. Wright, Jr., US. Pat.No. 2,858,840 issued Nov. 4, 1958, for instance. The outlet or deliveryside of the relay valve 105 is connected by a conduit 106 with thespring set portion 3 of the brake actuator 2, and the conduit 11a isconnected between the outlet port 35 of the control valve 12 and thecontrol side of said relay valve. Of course, the ratio-relay valve 105is operable in response to fluid pressure from the auxiliary emergencyreservoir 101 through the conduit 104, the inlet and delivery sides ofsaid ratio-relay valve and the conduit 106 to de-actuate the spring setportion f the brakeactuator 2, and it should be noted that the emergencyfluid pressure applied to said actuator is in a predetermined ratio,e.g. a 3:1 ratio, with the signal or control fluid pressure applied tosaid ratio-relay valve by said control valve.

A tractor-protector valve 107 of a-type well known in the art such asthat shown in the Cyril B. Fites US. Pat. No. 2,859,763 issued Nov. 11,I958, is also provided in the system 100 between the tractor and trailerportions thereof. The service portion of the tractor protector valve 107is interposed in a conduit 108 connected between the conduit 8a and atractor service gladhand 109 which is coupled with a trailer servicegladhand 109a, and the emergency portion of said tractor protector valveis interposed in a conduit 110 connected between the conduit 11a and atractor emergency gladhand 111 which is coupled with a trailer emergencygladhand 1110. A control conduit 112 is connected between the conduit104 and the control portion of the tractor protector valve 107, and apushpull valve 113 of the on-off" type well known in the art isinterposed in the conduit 112, said push-pull valve being movablebetween its on position providing open pressure fluid communicationthrough the conduit 112 to the control portion of the tractor protectorvalve 107 and its off position interrupting said pressure fluidcommunication and connecting the control portion of said tractorprotector valve to the atmosphere.

The trailer portion of the brake system includes a conduit 114 connectedbetween the trailer emergency gladhand 111a and the control side ofanother ratio-relay valve 115 of the same type as the ratio-relay valvepreviously discussed herein, and the outlet side of said ratio-relayvalve is connected by a conduit 116 with the spring set portion 3a of atrailer brake actuator 2a of the same type as "the brake actuator 2previously discussed herein. The inlet side of the ratiorelay valve 115is connectedwith a trailer emergency reservoir 117 by a conduit 118, andanother conduit 119 having a uni-directional or check valvel20'interposed therein is connected between said trailer emergencyreservoir and the conduit 114.

A trailer service reservoir 121 is also connected with the conduit 114by a conduit 122 having a protection valve 123 of a type well known 'inthe art interposed therein, said protection valve being a type of checkvalve which is spring loaded to permit fluid pressure flow therethroughin excess of a predetermined value, e.g. 30 psi, through the conduit 122to said trailer service reservoir. Anotherconduit 124 is connectedbetween the trailer service reservoir 12] and the inlet side of a relayvalve 125 of a type well known to the art, and the outlet side of saidrelay valve is connected with the trailer service or fluid pressureresponsive portion 4a of the trailer brake actuator 2a by a conduit126., To complete the description of the system 100, another serviceconduit 127 is interposed between the trailer service gladhand 109a andthe control side or portion of the relay valve 125.

In the operation of the system 100 with the control valve 12 actuated toits in position, fluid pressure flows from the emergency reservoir 10through conduits'll, 11a and said control valve to charge the controlportion of the ratio-relay valve 105 which is actuated or driven therebyto a wide open position effecting open or dumping pressure fluidcommunication or flow from the auxiliary emergency reservoir 101 throughthe conduits 104, 106 and said ratio-relay valve to the spring setportion 3 of the tractor brake actuator 2. In this manner, the fluidpressure so applied to the actuator spring set portion 3 effects thede-actuation thereof which results in the de-cnergization of the tractorbrakes, and it is, of course, apparent that the auxiliary emergencyreservoir 101 will be charged through the conduit 102 and its protectivecheck valve 103 with fluid pressure from the emergency reservoir 10.

With the push-pull valve 113 in its charging or on" position, pressurefluid also flows from the auxiliary emergency reservoir 101 through theconduits 104,

'112 and said push-pull valve to the control side of the tractorprotector valve 107 which serves to cock or maintain the service andemergency portions of said tractor protector valve open to providepressure fluid flow from the conduit 11a through the conduit 110, theemergency portion of said tractor protector valve, the tractor andtrailer emergency gladhands l 1 1, 1 11a and the conduit 114 to thecontrol portion or side of the ratio-relay valve 115 to effect actuationthereof. Of course, fluid pressure also flows from the conduit 114through conduits 119, 122 and the check and protector valves 120, 123therein to charge the trailer emergency and service reservoirs 1 17,121, respectively, The actuation of the ratio-relay valve 115 inresponse to the fluid pressure applied to the control side thereofdrives said ratio-relay valve to a wide open position effecting open ordumping pressure fluid communication between the inlet and outlet sidesthereof to effect an unmeter ed application of fluid pressure from thetrailer emergency reservoir 117 through the conduit 118 and saidratio-relay valve to the trailer brake actuator 2a in order to deactuatethe spring set portion 3a thereof and de-energize the trailer brakes(not shown).

With the tractor and trailer brake actuator spring set portions 3, 3a sode-actuated, the operator can now move the vehicle and effect servicebraking application to decelerate or stop the vehicle. For instance, anoperator applied force on the foot valve 9, meters fluid pres sure fromthe tractor service reservoir 7 through conduits 8 8a and said footvalve to the fluid pressure responsive motor 4 of the tractor actuator 2to effect service energization of the tractor brake associatedtherewith, and at the same time the metered service fluid pressure alsoflows through the conduit 108, the service portion of the tractorprotector valve 107, the tractor and trailer service gladhands 108, 108aand the conduit 127 to the control side or portion of the relay valve125 to effect metering actuation thereof. The relay valve 125 isresponsive to the fluid pressure metered to the control portion thereofto effect metered pressure fluid flow from the trailer service reservoir121 through the conduits 124, 126 and said relay valve to the trailerbrake actuator 2a in order to actuate the fluid pressure responsivemotor 4a thereof and effect service energization of the trailer brakes(not shown).

In the event of a fluid pressure failure in the service branch due tocompressor malfunction, slow leaks, or a ruptured conduit or the like,wherein the service fluid pressure is reduced to the aforementionedpredetermined value or eliminated, the control valve 12 functionsautomatically, as previously described hereinbefore, to isolate theconduit 11 and emergency reservoir 10 and vent the conduit 11a and thecontrol portion of the ratio-relay valve 105 to the atmosphere. Theratiorelay valve 105 is de-actuated in response to the venting of thecontrol portion thereof to isolate the conduit 104 and auxiliaryemergency reservoir 101 and vent the conduit 106 and the spring setportion 3 of the tractor actuator 2 to the atmosphere thereby actuatingsaid spring set portion and effecting spring setting energization of thetractor brakes. At the same time, the control portion of the ratio-relayvalve 115 is also exhausted to atmosphere through the conduit 114, theemergency gladhands 111, 111a, conduit 110 and the emergency portion ofthe tractor protector valve 107, the conduit 11a, and the automaticallyactuated control valve 12. The ratio-relay valve 115 is de-actuated inresponse to the venting of the control portion thereof to isolate theconduit 118 and the trailer emergency reservoir 117 and vent the conduit116 and the spring set portion 3a of the trailer brake actuator 2a tothe atmosphere thereby actuating said spring set portion and effecting aspring setting energization of the trailer brakes substantiallysimultaneously withe the spring setting energization of the tractorbrakes.

The overriding actuation of the control valve 12 by the operator, aspreviously described hereinbefore, reapplies the fluid pressureremaining in the emergency reservoir 10 therefrom to the controlportions of the ratio-relay valves 105, 115, respectively, in the samemanner as previously described; however, it should be noted that theprotection valve 123 will open at its predetermined pressure, e.g. 30p.s.i. to thereby limit the magnitude of the fluid pressure applied bythe override application of the control valve 12 during the emergencyconditions of an inoperative service branch 5. Nevertheless, since theratio-relay valves 105, 115 are of the ratio or multiplying types, theyare responsive to the relatively low override fluid pressures applied totheir control portions to meter anintensified or greater ratioed fluidpressure from the completely protected tractor and trailer emergencyreservoirs 101, 117 to the tractor and trailer brake actuators 2, 2a todeactuate the spring set portions 3, 30 thereof and effect an overridede-energization of the tractor and trailer brakes in order to effecttemporary movement of the vehicle to a safe or off-the-road positionuntil the service branch 5 can be repaired to once again preserve theintegrity of the system 100.

Referring now to FIG. 5, an alternative fluid pressure system 200 ispartially shown for use in the tractortrailer vehicle combination havingsubstantially the same component parts and functioning in substantiallythe same manner as the previously described system with the followingexceptions.

In the system 200, a biased two-way check valve or fluid pressureswitching valve 201 is connected between the service and emergencyreservoirs 7, 10 and the control valve 12. The outlet port of theswitching valve 201 is connected with the service port 34 of the controlvalve 12 by a conduit 202, and the inlet ports of said switching valveare connected with the service and emergency reservoirs 7, 10 byconduits 203, 204, respectively. To complete the description of thesystem 200, another conduit 205 is connected between the conduit 203 andthe control port of the switching valve 201; however, it should be notedthat the other components (not shown) of the system 200 are comparableto those of the system 100, but are omitted for the sake of expediency.

The switching valve 201, FIG. 6, is provided with a housing 206 having abore 207 carryinga seal 208 therein, and said bore is interposed betweenopposed counterbores 209, 210. The counterbores 209, 210 are closed byclosure members 21 1, 212 which are threadedly connected with thehousing 206, and a control port 213 which receives the conduit 205, aspreviously mentioned, is provided in the closure member 212 in pressurefluid communication with the counterbore 210. Spaced inlet ports 214,215 which receive the service and emergency conduits 203, 204, aspreviously mentioned, are provided in the housing 206 intersecting withthe counterbore 209, respectively, and said counterbore is undercut at216 between said inlet ports, said undercut being connected with anoutlet port 217 which receives the conduit 202, as previously mentioned.

A switch or valve control member 218 is slidably received in the boreand counterbore 208, 209 and extends coaxially into the counterbore 210,and peripheral seals 219, 220, 221 are carried in said valve controlmember. The seal 221 is sealably engaged with the counterbore 209between the inlet port 215 and the closure member 21, and the portionsof the counterbore 209 adjacent to the undercut 216 therein define valveseats for the seals or valve members 219, 220, respectively. A piston222 is connected with the leftward end of the valve control member 218by suitable means, such as the snap ring 223, and said piston carries aperipheral seal 224 in sealing engagement with the counterbore 210. Aspring 225 is biased between one side of the piston 222 and the housing206 in the counterbore 210, and an expansible control chamber 226 isdefined in said counterbore between said piston and the closure member212 in open pressure fluid communication with the control port 213.

With the component parts of the switch valve 201 positioned as shown inFIG. 6 and as described hereinabove, the service fluid pressure from theservice reservoir flows through the conduits 203, 205 and the controlport 213 of said switching valve into the control chamber 226 acting onthe effective area of the piston 222 to urge said piston rightwardlyagainst the compressive force of the spring 225 and engage the valvecontrol member 218 with the closure member 211. In this cocked position,the valve 220 is engaged with its cooperating valve seat to interruptpressure fluid communication between the-inlet and outlet ports 215,217, and the valve 219 is displaced from its cooperating valve seat toeffect pressure fluid flow from the service reservoir 7 through theconduit 203, the inlet port 214, counterbore 209, undercut 216 andoutlet port 217 of the switch valve 201 and therefrom through theconduit 202 to the inlet port 34 of the control valve 12.

In the event of the loss of the service fluid pressure in an emergencycondition, as previously mentioned, the compressive force of the spring225 drives the piston 222 leftwardly into engagement with the closuremember 212, and the valve control member 218 is concertedly movable withsaid piston to engage the valve 219 with its cooperating valve seatinterrupting pressure fluid communication between the inlet and outletports 214, 217 and disengages the valve 220 from its cooperating valveseat to establish pressure fluid communication between the inlet andoutlet ports 215, 217. In this manner the switching valve 201 isactuated to establish pressure fluid flow from the emergency reservoir10 through the conduit 204, the inlet port 215, counterbore 209,undercut 216 and outlet port 217 of said switching valve and therefromthrough the conduit 202 to the inlet port 34 of the control valve 12.

From the foregoing, it is now apparent that novel fluid pressure systems1, 100, 200 and control valves 12, 201 therefor meeting the objects andadvantages set out hereinbefore, as well as others, are provided andthat changes as to precise configurations set forth in the disclosure byway of illustration may be made by those skilled in the art withoutdeparting from the spirit of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A control valve comprising a housing, application means selectivelymovable in said housing in response to an operator applied force thereonbetween one position effecting the application through said housing offluid pressure supplied thereto and isolating the applied fluid pressurefrom the atmosphere and another position isolating the supplied andapplied fluid pressure and venting the applied fluid pressure to theatmosphere, other means movable in said housing between operative andinoperative positions and concertedly with and relative to saidapplication means including a pair of opposed end portions, one of saidopposed end portions defining with said housing an expansible controlfluid pressure chamber, and a bore in said other means between saidopposed end portions in which said application means is reciprocallyreceived, and abutment means on said application means for engagementwith said one opposed end portion, said abutment means and one opposedend portion being engaged to effect automatic concerted movement of saidapplication and other means toward their other and operative positionsand to effect selective concerted movement of said application and othermeans in response to an operator applied force on said application meanstoward their one and inoperative positions, respectively, when thecontrol fluid pressure in said chamber acting on said one opposed endportion is less than a predeter' mined value, and said application meansalso being selectively movable between its one and other positions inresponse to the operator applied force thereon relative to said othermeans in its inoperative position when the control fluid pressure insaid chamber acting on said one opposed end portion exceeds thepredetermined value.

2. A control valve comprising a. housing, application means selectivelymovable in said housing between two positions, and other means movablein said housing including a pair of opposed end portions, one of saidopposed end portions being subjected to control fluid pressure, a borein said other means intersecting with said opposed end portions in whichsaid application means is reciprocally received, and means on said oneopposed end portion defining an abutment for driving engagement withsaid application means, said other means being movable in response tocontrol fluid pressure less than a predetermined value acting on saidone opposed end portion to effect the driving engagement between saidabutment and application means and automatically urge said applicationmeans toward only one of its two positions.

3. A control valve comprising a housing, application means selectivelymovable in said housing in response to an operator applied force thereonbetween one position effecting the application through said housing offluid pressure supplied thereto and another position isolating thesupplied and applied fluid pressures and venting the applied fluidpressure, and other means movable in said housing including a pair ofopposed end portions, one of said end portions being subjected to acontrol fluid pressure, a bore in said other means intersecting withsaid opposed end portions through which said application means extends,and means on said one opposed end portion defining abutment means forengagement with said application means, said abutment means andapplication means being engaged to drive said other means with saidapplication means upon the selective movement thereof to its oneposition and also to drive said application means to its other positionwith said other means upon automatic movement thereof when the controlfluid pressure acting on said one of said opposed end portions is lessthan a predetermined value.

4. A control valve according to claim 3, wherein said other meansincludes resiliently urged means, said resiliently urged means beingmovable in response to its own force to drivingly engage said abutmentmeans and application means when the control fluid pressure acting onsaid one opposed end portion is less than the predetermined value.

5. A control valve according to claim 4, comprising an effective area onsaid one opposed end portion of said resiliently urged means subjectedto the control fluid pressure, said resiliently urged means beingmovable against its own force toward an inoperative position in saidhousing in response to the control fluid pressure in excess of thepredetermined value acting on said area, and said resiliently urgedmeans being movable in response to its own force toward an operativeposition in said housing engaging said abutment means and applicationmeans and driving said application means therewith to its other positionwhen the control fluid pressure acting on said area is less than thepredetermined value.

6. A control valve according to claim 5, comprising other abutment meanson said housing for engagement with the other of said opposed endportions of said resiliently urged means and defining the inoperativeposition thereof.

7. A control valve according to claim 5, comprising other abutment meanson said application means for engagement with said first named abutmentmeans, said first named and other abutment means being drivingly engagedto drive said application means to its other position upon the movementof said resiliently urged means to its operative position and to drivesaid resiliently urged means against its own force toward itsinoperative position in response to the selective applied force movementof said application means from its other position to its one positionwhen the control fluid pressure acting on said area is less than thepredetermined value, and said first named abutment means beingdisengaged from said other abutment means upon the movement of saidresiliently urged means to its inoperative position in response to thecontrol fluid pressure in excess of the predetermined value acting onsaid area and relative to said application means in its other position.

8. A control valve according to claim 4, wherein said resiliently urgedmeans includes a piston means movable in said housing, spring meansengaged with said piston means and urging said abutment means towardengagement with said application means, and said one opposed end portiondefining an effective area on said piston means subjected to the controlfluid pressure, said piston means being movable against said springmeans toward an inoperative position in said housing in response to thecontrol fluid pressure in excess of the 9. A control valve according toclaim 4, wherein said one opposed: end portion defines with said housingan expansible control chamber subjected to the control fluid pressure.

10. A control valve according to claim 3, wherein said application meansincludes a pair of valve means for controlling pressure fluidcommunication between the supplied and applied fluid pressures andbetween the applied fluid pressure and the atmosphere, said valve meansbeing concertedly movable with said application means from its otherposition interrupting pressure fluid communication between the suppliedand applied fluid pressures and establishing pressure fluidcommunication between the applied fluid pressure and the atmospheretoward the one position of said application means to establish pressurefluid communication between the supplied and applied fluid pressures andinterrupt pressure fluid communication between the supplied fluidpressure and the atmosphere, respectively.

11. A control valve according to claim 10, comprising a pair of valveseats on said housing for engagement with said valve means,respectively, one of said valve means being engaged with one of saidvalve seats and the other of said valve means beingdisengaged from theother of said valve seats when said application means is in one and theother of its one and other positions, respectively.

12. A control valve according to claim 3, comprising a pair of opposedholding areas on said application means subjected to the applied andsupplied fluid pressures when said application means is in its one andother positions, respectively, the supplied fluid pressure acting on oneof said areas to establish a holding force urging said application meansin a direction toward its other position when said application means isin its other position and the applied fluid pressure acting on the otherof said areas to establish another holding force opposed to said firstnamed holding force urging said application means in a direction towardits one position when said application means is in its one position.

13. A control valve comprising a housing having inlet, outlet andexhaust ports therein, means selectively movable in said housing inresponse to an operator applied force thereon between one positionestablishing pressure fluid communication between said inlet and outletports and interrupting pressure fluid communication between said outletand exhaust ports and another position interrupting pressure fluidcommunication between said inlet and outlet ports and establishingpressure fluid communication between said outlet and exhaust ports, acontrol port in said housing, other means movable in said housingbetween opposed operative and inoperative positions and concertedly withand relative to said first named means and including a pair of opposedend portions, one of said opposed end portions being subjected to thefluid pressure at said control port, a bore in said other meansintersecting with said opposed end portions and through which said firstnamed means extends, and means on said one opposed end portion definingan abutment for driving engagement with said first named means, saidother means and first named means being automatically and selectivelymovable to drivingly engage said abutment and first named means whereinsaid other means and first named means are thereafter concertedlymovable toward their operative and other positions and toward theirinoperative and one positions, respectively, when the fluid pressure atsaid control port acting on said other means is less than apredetermined value, and said first named means being selectivelymovable in response to the operator applied force between its one andother positions relative to said other means in its inoperative positionupon the movement of said other means thereto relative to said firstnamed means in its other position when the fluid pressure at saidcontrol port acting on said other means is in excess of thepredetermined value.

14. A control valve comprising a housing having inlet, outlet andexhaust ports therein, means selectively movable in said housing forcontrolling pressure fluid.

communication between said inlet and outlet ports and between saidoutlet and exhaust ports, a control port in said housing, and othermeans movable in said housing between operative and inoperativepositions including a pair of opposed end portions, one of said opposedend portions being subjected to the fluid pressure at said control port,a bore in said other means intersecting with said opposed end portionsand through which said first named means extends, and abutment means onsaid one opposed end portion for driving engagement with said firstnamed means, said other means being movable toward its operativeposition in response to fluid pressure at said control port less than apredetermined value to effect the driving engagment of said abutmentmeans with said first named means and drive said first named meanstoward a position interrupting pressure fluid communication between saidinlet and outlet ports and establishing pressure fluid communicationbetween said outlet and exhaust ports, and said abutment means and firstnamed means being drivingly engaged to effect the concerted movement ofsaid other means toward its inoperative position with said first namedmeans upon the selective movement thereof from its last named positiontoward another position establishing pressure fluid communicationbetween said inlet and outlet ports and interrupting pressure fluidcommunication between said outlet and exhaust ports when the fluidpressure at said control port is less than the predetermined value.

15. A control valve comprising a housing having inlet, outlet andexhaust ports therein, means selectively movable in said housing forcontrolling pressure fluid communication between said ports, said meansbeing movable in response to an operator applied force thereon towardone position establishing pressure fluid communication between saidinlet and outlet ports and interrupting pressure fluid communicationbetween said outlet and exhaust ports and also toward another positionto interrupt pressure fluid communication between said inlet and outletports and establishing pressure fluid communication between said outletand exhaust ports, a control port in said housing, and resiliently urgedmeans subjected to fluid pressure at said control port and movable insaid housing for driving and driven engagement with said first namedmeans, a bore in said resiliently urged means through which said firstnamed means extends, said resiliently urged means being driven againstits own force by said first named means upon the selective movementthereof toward its one position and said resiliently urged means alsobeing movable in response to its own force to drive said first namedmeans toward its other position when the fluid pressure at said controlport acting on said resiliently urged means is less than a predeterminedvalue.

16. A control valve according to claim 15, comprising means on saidapplication means and resiliently urged means defining opposed abutmentmeans for the driving and driven engagement thereof.

17. A control valve according to claim 15, comprising abutment means onsaid housing for engagement with said resiliently urged means, saidfirst named means being selectively movable in response to the operatorapplied force thereon between its one and other positions relative tosaid resiliently urged means upon the movement of said resiliently urgedmeans relative to said first named means in its other position intoengagement with said abutment means when the fluid pressure at saidcontrol port acting on said resiliently urged means exceeds thepredetermined value.

18. A control valve according to claim 15, comprising an abutment onsaid housing for engagement with said resiliently urged means anddefining the inoperative position thereof, said resiliently urged meansbeing movable in response to the fluid pressure at said control port inexcess of the predetermined value toward engagement with said abutment.

19. A control valve according to claim 15, comprising an effective areaon said resiliently urged means subjected to the fluid pressure at saidcontrol port, said resiliently urged means being movable against its ownforce and relative to said first named means in its other positiontoward an inoperative position on said housing in response to fluidpressure at said control port in excess of the predetermined valueacting on said area, and said resiliently urged means being movable inresponse to its own force toward an operative position in said housingdriving said first named means therewith from its one position to isother position when the fluid pressure at said control port acting onsaid area is less than the predetermined value.

20. A control valve according to claim 19, wherein said resilientlyurged means includes piston means movable in said housing, said borebeing in said piston means, abutment means on said piston means for thedriving and driven engagement with said first named means, spring meansengaged with said piston means urging said abutments toward engagementwith said first named means,and said area being defined on said pistonmeans, said piston means being movable against the force of said springmeans toward its inoperative position and disengaging said abutmentmeans from said first named means in its other position when the fluidpressure at said control port acting on said area is in excess of thepredetermined value, and said piston means being movable toward itsoperative position in response to the force of said spring means toeffect the driving engagement of said abutment means with said firstnamed means in its one position and the concerted driving thereof to itsother position when the fluid pressure at said control port acting onsaid area is less than the predetermined value.

21. A control valve according to claim 20, comprising opposed endportions on said piston means, said bore intersecting with said opposedend portions, one of said opposed end portions including said abutmentmeans and said area and defining with said housing an expansible controlchamber connected in pressure fluid communication with said controlport, and other abutment means on said housing for engagement with saidpiston means and defining the inoperative position thereof.

22. A control valve according to claim 21, comprising another bore and acounterbore in said housing connected with said inlet port and saidoutlet and exhaust ports, respectively, a first valve seat defined insaid bore between said inlet and outlet ports, a second valve seatdefined in said counterbore between said outlet and exhaust ports, saidfirst named means including a rod member having opposed end portions,said rod member being slidable in said piston and other bores andextending coaxially through said control chamber, one of said endportions extending exteriorly of said housing for receiving the operatorapplied force and the other of said end portions including spaced firstand second valve means for engagement with said first and second valveseats respectively, said first and second valve means being engaged withand disengaged from said first and second valve seats to interrupt thepressure fluid communication between said inlet and outlet ports andestablish the pressure fluid communication between said outlet andexhaust ports, respectively, when said first named means is in its oneposition, and said first and second valve means being disengaged fromand engaged with said first and second valve seat to establish thepressure fluid communication between said inlet and outlet ports andinterrupt the pressure fluid communication between the outlet andexhaust ports, respectively, when said first named means is in its otherposition.

23. A control valve comprising a housing, inlet, outlet and exhaustchambers in said housing, application means selectively movable in saidhousing in response to an operator applied force thereon for controllingcommunication between said chambers, said application means beingselectively movable between one position isolating said inlet and outletchambers and communicating said outlet and exhaust chambers and anotherposition communicating said inlet and outlet chambers and isolating saidoutlet and exhaust chambers, piston means movable in said housing anddefining therewith an expansible fluid pressure control chamber, a borein said piston means, said application means extending coaxially throughsaid bore and said control chamber, abutment means on said piston meansfor driving and driven engagement with said application means, andspring means contained between said piston means and said housing urgingsaid piston means in one direction to engage said abutment means withsaid application means and oppose fluid pressure expansion of saidcontrol chamber, said spring means urging said piston means in the onedirection to effect the driving engagement between said abutment meansand application means and drive said application means from its one toits other position and said application means being selectively movablefrom its other position toward its one position in response to theoperator applied force thereon to also effect the driving engagementthereof with said abutment means and drive said piston means in anotherdirection opposite the one direction against said spring means when thefluid pressure in said control chamber acting on said piston means isless than a predetermined value, and said application means beingselectively movable in response to the operator applied force betweenits one and other positions relative to said piston means upon themovement of said piston means against said spring means and relative tosaid application means toward a position in said housing disengagingsaid abutment means from said application means when the fluid pressurein said control chamber acting on said piston means is in excess of thepredetermined value.

24. A control valve comprising a housing, application means selectivelymovable in said housing in response to an operator applied force thereonbetween one position effecting the application through said housing offluid pressure supplied thereto and another position isolating thesupplied and applied fluid pressures and venting the applied fluidpressure, other means subjected to a control fluid pressure and movablein said housing for driving and driven engagement with said applicationmeans in its one and other positions, respectively, said other meansbeing driven by said application means upon the selective movementthereof to its one position and said other means also being movable toautomatically drive said application means to its other position whenthe control fluid pressure acting on said other means is in excess ofand less than a predetermined value, respectively, and a pair of opposedholding areas on said application means respectively subjected to theapplied and supplied fluid pressures when said application means is inits one and other positions, the supplied and applied fluid pressuresacting on one of said areas and the other of said areas to establish oneand other holding forces urging said application means towards its oneand other positions when said application means is in its one and otherposition, respectively, and one of said one and other holding forcesbeing eliminated subsequent to the establishment of the other thereof.

1. A control valve comprising a housing, application means selectivelymovable in said housing in response to an operator applied force thereonbetween one position effecting the application through said housing offluid pressure supplied thereto and isolating the applied fluid pressurefrom the atmosphere and another position isolating the supplied andapplied fluid pressure and venting the applied fluid pressure to theatmosphere, other means movable in said housing between operative andinoperative positions and concertedly with and relative to saidapplication means including a pair of opposed end portions, one of saidopposed end portions defining with said housing an expansible controlfluid pressure chamber, and a bore in said other means between saidopposed end portions in which said application means is reciprocallyreceived, and abutment means on said application means for engagementwith said one opposed end portion, said abutment means and one opposedend portion being engaged to effect automatic concerted movement of saidapplication and other means toward their other and operative positionsand to effect selective concerted movement of said application and othermeans in response to an operator applied force on said application meanstoward their one and inoperative positions, respectively, when thecontrol fluid pressure in said chamber acting on said one opposed endportion is less than a predetermined value, and said application meansalso being selectively movable between its one and other positions inresponse to the operator applied force thereon relative to said othermeans in its inoperative position when the control fluid pressure insaid chamber acting on said one opposed end portion exceeds thepredetermined value.
 2. A control valve comprising a housing,application means selectively movable in said housing between twopositions, and other means movable in said housing including a pair ofopposed end portions, one of said opposed end portions being subjectedto control fluid pressure, a bore in said other means intersecting withsaid opposed end portions in which said application means isreciprocally received, and means on said one opposed end portiondefining an abutment for driving engagement with said application means,said other means being movable in response to control fluid pressureless than a predetermined value acting on said one opposed end portionto effect the driving engagement between said abutment and applicationmeans and automatically urge said application means toward only one ofits two positions.
 3. A control valve comprising a housing, applicationmeans selectively movable in said housing in response to an operatorapplied force thereon between one position effecting the applicationthrough said housing of fluid pressure supplied thereto and anotherposition isolating the supplied and applied fluid pressures and Ventingthe applied fluid pressure, and other means movable in said housingincluding a pair of opposed end portions, one of said end portions beingsubjected to a control fluid pressure, a bore in said other meansintersecting with said opposed end portions through which saidapplication means extends, and means on said one opposed end portiondefining abutment means for engagement with said application means, saidabutment means and application means being engaged to drive said othermeans with said application means upon the selective movement thereof toits one position and also to drive said application means to its otherposition with said other means upon automatic movement thereof when thecontrol fluid pressure acting on said one of said opposed end portionsis less than a predetermined value.
 4. A control valve according toclaim 3, wherein said other means includes resiliently urged means, saidresiliently urged means being movable in response to its own force todrivingly engage said abutment means and application means when thecontrol fluid pressure acting on said one opposed end portion is lessthan the predetermined value.
 5. A control valve according to claim 4,comprising an effective area on said one opposed end portion of saidresiliently urged means subjected to the control fluid pressure, saidresiliently urged means being movable against its own force toward aninoperative position in said housing in response to the control fluidpressure in excess of the predetermined value acting on said area, andsaid resiliently urged means being movable in response to its own forcetoward an operative position in said housing engaging said abutmentmeans and application means and driving said application means therewithto its other position when the control fluid pressure acting on saidarea is less than the predetermined value.
 6. A control valve accordingto claim 5, comprising other abutment means on said housing forengagement with the other of said opposed end portions of saidresiliently urged means and defining the inoperative position thereof.7. A control valve according to claim 5, comprising other abutment meanson said application means for engagement with said first named abutmentmeans, said first named and other abutment means being drivingly engagedto drive said application means to its other position upon the movementof said resiliently urged means to its operative position and to drivesaid resiliently urged means against its own force toward itsinoperative position in response to the selective applied force movementof said application means from its other position to its one positionwhen the control fluid pressure acting on said area is less than thepredetermined value, and said first named abutment means beingdisengaged from said other abutment means upon the movement of saidresiliently urged means to its inoperative position in response to thecontrol fluid pressure in excess of the predetermined value acting onsaid area and relative to said application means in its other position.8. A control valve according to claim 4, wherein said resiliently urgedmeans includes a piston means movable in said housing, spring meansengaged with said piston means and urging said abutment means towardengagement with said application means, and said one opposed end portiondefining an effective area on said piston means subjected to the controlfluid pressure, said piston means being movable against said springmeans toward an inoperative position in said housing in response to thecontrol fluid pressure in excess of the predetermined value acting onsaid area and relative to said application means in its other position,and said piston means being movable toward an operative position in saidhousing in response to the force of said spring means to effect thedriving engagement of said abutment means with said application means inits one position and move said application means to its other positionwhen the control fluid pressure aCting on said area is less than thepredetermined value.
 9. A control valve according to claim 4, whereinsaid one opposed end portion defines with said housing an expansiblecontrol chamber subjected to the control fluid pressure.
 10. A controlvalve according to claim 3, wherein said application means includes apair of valve means for controlling pressure fluid communication betweenthe supplied and applied fluid pressures and between the applied fluidpressure and the atmosphere, said valve means being concertedly movablewith said application means from its other position interruptingpressure fluid communication between the supplied and applied fluidpressures and establishing pressure fluid communication between theapplied fluid pressure and the atmosphere toward the one position ofsaid application means to establish pressure fluid communication betweenthe supplied and applied fluid pressures and interrupt pressure fluidcommunication between the supplied fluid pressure and the atmosphere,respectively.
 11. A control valve according to claim 10, comprising apair of valve seats on said housing for engagement with said valvemeans, respectively, one of said valve means being engaged with one ofsaid valve seats and the other of said valve means being disengaged fromthe other of said valve seats when said application means is in one andthe other of its one and other positions, respectively.
 12. A controlvalve according to claim 3, comprising a pair of opposed holding areason said application means subjected to the applied and supplied fluidpressures when said application means is in its one and other positions,respectively, the supplied fluid pressure acting on one of said areas toestablish a holding force urging said application means in a directiontoward its other position when said application means is in its otherposition and the applied fluid pressure acting on the other of saidareas to establish another holding force opposed to said first namedholding force urging said application means in a direction toward itsone position when said application means is in its one position.
 13. Acontrol valve comprising a housing having inlet, outlet and exhaustports therein, means selectively movable in said housing in response toan operator applied force thereon between one position establishingpressure fluid communication between said inlet and outlet ports andinterrupting pressure fluid communication between said outlet andexhaust ports and another position interrupting pressure fluidcommunication between said inlet and outlet ports and establishingpressure fluid communication between said outlet and exhaust ports, acontrol port in said housing, other means movable in said housingbetween opposed operative and inoperative positions and concertedly withand relative to said first named means and including a pair of opposedend portions, one of said opposed end portions being subjected to thefluid pressure at said control port, a bore in said other meansintersecting with said opposed end portions and through which said firstnamed means extends, and means on said one opposed end portion definingan abutment for driving engagement with said first named means, saidother means and first named means being automatically and selectivelymovable to drivingly engage said abutment and first named means whereinsaid other means and first named means are thereafter concertedlymovable toward their operative and other positions and toward theirinoperative and one positions, respectively, when the fluid pressure atsaid control port acting on said other means is less than apredetermined value, and said first named means being selectivelymovable in response to the operator applied force between its one andother positions relative to said other means in its inoperative positionupon the movement of said other means thereto relative to said firstnamed means in its other position when the fluid pressure at saidcontrol port acting on said other meaNs is in excess of thepredetermined value.
 14. A control valve comprising a housing havinginlet, outlet and exhaust ports therein, means selectively movable insaid housing for controlling pressure fluid communication between saidinlet and outlet ports and between said outlet and exhaust ports, acontrol port in said housing, and other means movable in said housingbetween operative and inoperative positions including a pair of opposedend portions, one of said opposed end portions being subjected to thefluid pressure at said control port, a bore in said other meansintersecting with said opposed end portions and through which said firstnamed means extends, and abutment means on said one opposed end portionfor driving engagement with said first named means, said other meansbeing movable toward its operative position in response to fluidpressure at said control port less than a predetermined value to effectthe driving engagment of said abutment means with said first named meansand drive said first named means toward a position interrupting pressurefluid communication between said inlet and outlet ports and establishingpressure fluid communication between said outlet and exhaust ports, andsaid abutment means and first named means being drivingly engaged toeffect the concerted movement of said other means toward its inoperativeposition with said first named means upon the selective movement thereoffrom its last named position toward another position establishingpressure fluid communication between said inlet and outlet ports andinterrupting pressure fluid communication between said outlet andexhaust ports when the fluid pressure at said control port is less thanthe predetermined value.
 15. A control valve comprising a housing havinginlet, outlet and exhaust ports therein, means selectively movable insaid housing for controlling pressure fluid communication between saidports, said means being movable in response to an operator applied forcethereon toward one position establishing pressure fluid communicationbetween said inlet and outlet ports and interrupting pressure fluidcommunication between said outlet and exhaust ports and also towardanother position to interrupt pressure fluid communication between saidinlet and outlet ports and establishing pressure fluid communicationbetween said outlet and exhaust ports, a control port in said housing,and resiliently urged means subjected to fluid pressure at said controlport and movable in said housing for driving and driven engagement withsaid first named means, a bore in said resiliently urged means throughwhich said first named means extends, said resiliently urged means beingdriven against its own force by said first named means upon theselective movement thereof toward its one position and said resilientlyurged means also being movable in response to its own force to drivesaid first named means toward its other position when the fluid pressureat said control port acting on said resiliently urged means is less thana predetermined value.
 16. A control valve according to claim 15,comprising means on said application means and resiliently urged meansdefining opposed abutment means for the driving and driven engagementthereof.
 17. A control valve according to claim 15, comprising abutmentmeans on said housing for engagement with said resiliently urged means,said first named means being selectively movable in response to theoperator applied force thereon between its one and other positionsrelative to said resiliently urged means upon the movement of saidresiliently urged means relative to said first named means in its otherposition into engagement with said abutment means when the fluidpressure at said control port acting on said resiliently urged meansexceeds the predetermined value.
 18. A control valve according to claim15, comprising an abutment on said housing for engagement with saidresiliently urged means and defining the inoperative position thereof,said resilienTly urged means being movable in response to the fluidpressure at said control port in excess of the predetermined valuetoward engagement with said abutment.
 19. A control valve according toclaim 15, comprising an effective area on said resiliently urged meanssubjected to the fluid pressure at said control port, said resilientlyurged means being movable against its own force and relative to saidfirst named means in its other position toward an inoperative positionon said housing in response to fluid pressure at said control port inexcess of the predetermined value acting on said area, and saidresiliently urged means being movable in response to its own forcetoward an operative position in said housing driving said first namedmeans therewith from its one position to is other position when thefluid pressure at said control port acting on said area is less than thepredetermined value.
 20. A control valve according to claim 19, whereinsaid resiliently urged means includes piston means movable in saidhousing, said bore being in said piston means, abutment means on saidpiston means for the driving and driven engagement with said first namedmeans, spring means engaged with said piston means urging said abutmentstoward engagement with said first named means,and said area beingdefined on said piston means, said piston means being movable againstthe force of said spring means toward its inoperative position anddisengaging said abutment means from said first named means in its otherposition when the fluid pressure at said control port acting on saidarea is in excess of the predetermined value, and said piston meansbeing movable toward its operative position in response to the force ofsaid spring means to effect the driving engagement of said abutmentmeans with said first named means in its one position and the concerteddriving thereof to its other position when the fluid pressure at saidcontrol port acting on said area is less than the predetermined value.21. A control valve according to claim 20, comprising opposed endportions on said piston means, said bore intersecting with said opposedend portions, one of said opposed end portions including said abutmentmeans and said area and defining with said housing an expansible controlchamber connected in pressure fluid communication with said controlport, and other abutment means on said housing for engagement with saidpiston means and defining the inoperative position thereof.
 22. Acontrol valve according to claim 21, comprising another bore and acounterbore in said housing connected with said inlet port and saidoutlet and exhaust ports, respectively, a first valve seat defined insaid bore between said inlet and outlet ports, a second valve seatdefined in said counterbore between said outlet and exhaust ports, saidfirst named means including a rod member having opposed end portions,said rod member being slidable in said piston and other bores andextending coaxially through said control chamber, one of said endportions extending exteriorly of said housing for receiving the operatorapplied force and the other of said end portions including spaced firstand second valve means for engagement with said first and second valveseats respectively, said first and second valve means being engaged withand disengaged from said first and second valve seats to interrupt thepressure fluid communication between said inlet and outlet ports andestablish the pressure fluid communication between said outlet andexhaust ports, respectively, when said first named means is in its oneposition, and said first and second valve means being disengaged fromand engaged with said first and second valve seat to establish thepressure fluid communication between said inlet and outlet ports andinterrupt the pressure fluid communication between the outlet andexhaust ports, respectively, when said first named means is in its otherposition.
 23. A control valve comprising a housing, inlet, outlet andexhAust chambers in said housing, application means selectively movablein said housing in response to an operator applied force thereon forcontrolling communication between said chambers, said application meansbeing selectively movable between one position isolating said inlet andoutlet chambers and communicating said outlet and exhaust chambers andanother position communicating said inlet and outlet chambers andisolating said outlet and exhaust chambers, piston means movable in saidhousing and defining therewith an expansible fluid pressure controlchamber, a bore in said piston means, said application means extendingcoaxially through said bore and said control chamber, abutment means onsaid piston means for driving and driven engagement with saidapplication means, and spring means contained between said piston meansand said housing urging said piston means in one direction to engagesaid abutment means with said application means and oppose fluidpressure expansion of said control chamber, said spring means urgingsaid piston means in the one direction to effect the driving engagementbetween said abutment means and application means and drive saidapplication means from its one to its other position and saidapplication means being selectively movable from its other positiontoward its one position in response to the operator applied forcethereon to also effect the driving engagement thereof with said abutmentmeans and drive said piston means in another direction opposite the onedirection against said spring means when the fluid pressure in saidcontrol chamber acting on said piston means is less than a predeterminedvalue, and said application means being selectively movable in responseto the operator applied force between its one and other positionsrelative to said piston means upon the movement of said piston meansagainst said spring means and relative to said application means towarda position in said housing disengaging said abutment means from saidapplication means when the fluid pressure in said control chamber actingon said piston means is in excess of the predetermined value.
 24. Acontrol valve comprising a housing, application means selectivelymovable in said housing in response to an operator applied force thereonbetween one position effecting the application through said housing offluid pressure supplied thereto and another position isolating thesupplied and applied fluid pressures and venting the applied fluidpressure, other means subjected to a control fluid pressure and movablein said housing for driving and driven engagement with said applicationmeans in its one and other positions, respectively, said other meansbeing driven by said application means upon the selective movementthereof to its one position and said other means also being movable toautomatically drive said application means to its other position whenthe control fluid pressure acting on said other means is in excess ofand less than a predetermined value, respectively, and a pair of opposedholding areas on said application means respectively subjected to theapplied and supplied fluid pressures when said application means is inits one and other positions, the supplied and applied fluid pressuresacting on one of said areas and the other of said areas to establish oneand other holding forces urging said application means towards its oneand other positions when said application means is in its one and otherposition, respectively, and one of said one and other holding forcesbeing eliminated subsequent to the establishment of the other thereof.